losLab PDF Library offre ai team Delphi e C++Builder un motore PDF con sorgente disponibile per workflow desktop, server, DLL, ActiveX e Dylib, con controlli PDF/A e PDF/UA integrati, supporto PAdES e scelta dei renderer senza un servizio PDF esterno.
Questo articolo è rivolto a teams that need to create, inspect, and validate signed PDF workflows inside Delphi applications. Tratta PAdES signing and validation come ingegneria documentale di produzione, non come una semplice chiamata al componente.
Il rischio pratico è che signature creation and signature validation are often implemented separately, causing mismatched trust decisions when timestamps, revocation data, or incremental updates change. Per questo il flusso richiede un contratto scritto, diagnostica osservabile e file di regressione realistici.
Decisioni architetturali
Use one trust policy for signing and validation. accepted certificate stores, chain policy, timestamp source, and revocation source / PAdES profile, long-term validation requirements, and archive retention period
- accepted certificate stores, chain policy, timestamp source, and revocation source
- PAdES profile, long-term validation requirements, and archive retention period
- whether warnings create a block, manual review, or documented waiver
- how later document changes are restricted after the trusted revision
Percorso di implementazione
Validate the final signed revision, not the draft. The order below keeps the workflow reviewable for Delphi and C++Builder teams.
- prepare the document and collect validation prerequisites before signing
- apply the signature, timestamp, and revocation evidence according to policy
- validate the final signed file and classify every warning
- store trust evidence with the business record rather than only inside the PDF
- revalidate representative files when trust anchors or policy change
Evidenze di validazione
Trust evidence for signed documents. Keep these fields with the output or support record.
- signature status, byte range, digest algorithm, signer certificate, and chain result
- timestamp token status, revocation source, DSS/VRI presence, and validation time
- policy version, warning classification, and waiver decision
- final signed file hash and validator result
Long-term validation needs supporting data
PAdES workflows need certificate-chain checks, timestamps, revocation data, DSS/VRI information, byte-range validation, and policy decisions for warnings. The final file must be validated after all signing bytes are written.
Customer-visible behavior
Users do not see internal call order. They see whether the file opens, validates, prints, edits, imports, or gets rejected. The workflow should translate PAdES signing and validation results into states users can act on.
- prepare the document and collect validation prerequisites before signing
- apply the signature, timestamp, and revocation evidence according to policy
- validate the final signed file and classify every warning
- a signature can be cryptographically intact but untrusted by current policy
- revocation services may be unavailable when the document is signed
Engineering review notes for PAdES signing and validation
Use these review notes to make sure the feature has moved beyond a demo and can be defended during release, support, and customer escalation.
- Decision: accepted certificate stores, chain policy, timestamp source, and revocation source. Implementation pressure point: apply the signature, timestamp, and revocation evidence according to policy. Acceptance evidence: policy version, warning classification, and waiver decision. Regression trigger: clock differences can make timestamp and certificate validity hard to explain
- Decision: PAdES profile, long-term validation requirements, and archive retention period. Implementation pressure point: validate the final signed file and classify every warning. Acceptance evidence: final signed file hash and validator result. Regression trigger: a signature can be cryptographically intact but untrusted by current policy
- Decision: whether warnings create a block, manual review, or documented waiver. Implementation pressure point: store trust evidence with the business record rather than only inside the PDF. Acceptance evidence: signature status, byte range, digest algorithm, signer certificate, and chain result. Regression trigger: revocation services may be unavailable when the document is signed
Casi limite
- a signature can be cryptographically intact but untrusted by current policy
- revocation services may be unavailable when the document is signed
- incremental updates after signing need a clear allowed-change policy
- clock differences can make timestamp and certificate validity hard to explain
Delphi / C++Builder notes
PDFlibPas should sit behind a small service boundary that receives files, streams, profiles, and credentials, then returns output paths, warnings, metrics, and validation status. Important terms include PAdES, signature validation, timestamp, revocation, DSS, byte range.
Esempio di codice Delphi
Il seguente schema Delphi mostra un confine di servizio pratico per questo argomento. Mantieni controlli di policy, logging e validazione fuori dal blocco ristretto che chiama il prodotto, così il flusso resta verificabile.
procedure ValidatePadesPackage(const InputFile: string; const TrustPolicy: TTrustPolicy);
var
Pdf: TPDFlib;
ProcessId: Integer;
begin
Pdf := TPDFlib.Create;
try
ProcessId := Pdf.NewSignProcessFromFile(InputFile, '');
CheckByteRange(Pdf, ProcessId);
ValidateCertificatePath(Pdf, ProcessId, TrustPolicy);
Pdf.ReleaseSignProcess(ProcessId);
finally
Pdf.Free;
end;
end;Checklist di produzione
- Run the workflow on an empty file, a normal customer file, and a worst-case file
- Open the generated PDF with the target viewer, validator, printer, or downstream application
- Log product version, profile version, input hash, output path, elapsed time, and warning count
- Keep passwords, certificates, temporary files, and customer data under explicit retention rules
- Add regression documents when a customer file exposes a new edge case